is adobe flash player safe to use on an Imac?

Yes but,,,, you should only download and install it directly from Adobe and not thru some other prompt or source.

https://get.adobe.com/flashplayer/

If you install it, only update from the Updates tab of Flash Player system preference. There are many fake Flash update pop-ups that will install malware.

Yes, if ONLY gotten from Adobe.com however it is now pretty outdated and does not really enhance much any more.